In answer to this question, posed by O.R. John on the XLForum: “IXL2Relax, you said that you prefer to eliminate the parts like the ones I have. In all seriousness - why? I am wondering because I have not been happy with how my bike sometimes runs. Before I tell you what I don't like, I want to see if the reasons you don't like DynoJet parts are the same things I don't like about how my bike runs.”

IXL2Relax replied in Post#20 of this XLForum Thread: http://xlforum.net/forums/showthread.php?t=1792262

Well - my recommendation is based on user reports - Back when sportster.org was operating, there was a lot of interest in mods and people found certain ways to 'Enhance Performance'. The definition was mostly subjective and like many things in life, we want our money to buy what we intended, so our perspective is somewhat altered once we buy something (or buy into something). We usually find a way to like or justify what we spent our money or time on.

Over the years many of the previous recommendations (some settled wisdom) has proven that the mods 'enhance' some portion of the operation at the expense of other portions - So, you might get great throttle response when you wack it open at 3000 RPMs, but trying to cruise at 45 mph thru the countryside is now met with surging/sluggishness - or even wacking the throttle at 2500 RPMs is now a bog. The mods did 'enhance performance' for one portion of the operation.

The wisdom that has been gained with longer-term experience is that most riders want 90% good performance all the time, rather than 100% sometimes & 70% the other times. Which leads us back to the stock parts which were DESIGNED to provide good performance over the entire operating range of the carb (with only a few slight mods & adjustments needed).

We know HD 'tunes' the carb (picks parts & makes adjustments) to satisfy the EPA regs - not for the best response or acceleration or compatibility with open air filters or exhausts - So that limitation needs to be addressed (on a 1200, usually a 45 Slow Jet, a change to the IMS & installation of an N65C needle for the 1200 engines will get you close enough to begin final tweaking). Beyond that, unless you're going to spend dyno time tuning for some peak function in a specific portion of the operating range, you probably only need to make sure you're not too lean at WOT (usually a 175 or 180/185 Main will put you in the right ballpark for a 1200). Tweaking the tune based on the burn of the plugs will help you get even closer.

Most riders (and even many tuners) don't understand how getting the idle/transfer circuits right will lead to a much better performing carb in the entire rest of the range (WOT you're just dumping Air/Fuel to keep it exploding). So my advice, no matter what parts you have, is get that Idle/Transfer right because you'll be using that function most of the time, especially when cruising.

I'm not saying the DJ or Yost or other kits can't be somewhat functional for some part of the operating range - some riders are happy with those mods and live with the altered limitations they bring. The user reports over the years indicate that almost all those mods DO create other unintended consequences in the overall carb operation. If revving & racing is all you want to do - Go for it!

But most riders want something running good in all-around operation. My advice is targetted toward that goal.

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